Enhancing effects of acute exposure to cannabis smoke on working memory performance

Abstract

Numerous preclinical studies show that acute cannabinoid administration impairs cognitive performance. Almost all of this research has employed cannabinoid injections, however, whereas smoking is the preferred route of cannabis administration in humans. The goal of these experiments was to systematically determine how acute exposure to cannabis smoke affects working memory performance in a rat model. Adult male (n = 15) and female (n = 16) Long-Evans rats were trained in a food-motivated delayed response working memory task. Prior to test sessions, rats were exposed to smoke generated by burning different numbers of cannabis or placebo cigarettes, using a within-subjects design. Exposure to cannabis smoke had no effect on male rats’ performance, but surprisingly, enhanced working memory accuracy in females, which tended to perform less accurately than males under baseline conditions. In addition, cannabis smoke enhanced working memory accuracy in a subgroup of male rats that performed comparably to the worst-performing females. Exposure to placebo smoke had no effect on performance, suggesting that the cannabinoid content of cannabis smoke was critical for its effects on working memory. Follow-up experiments showed that acute administration of either Δ9-tetrahydrocannabinol (0.0, 0.3, 1.0, 3.0 mg/kg) or the cannabinoid receptor type 1 antagonist rimonabant (0.0, 0.2, 0.6, 2.0 mg/kg) impaired working memory performance. These results indicate that differences in the route, timing, or dose of cannabinoid administration can yield distinct cognitive outcomes, and highlight the need for further investigation of this topic.

Testicular hormones mediate robust sex differences in impulsive choice in rats

“…This finding is consistent with those from previous studies of sex differences in decision making involving risk of punishment or delayed punishment, in which estrous cycle does not modulate choice behavior ( Orsini et al, 2016 ; Liley et al, 2019 ). Similarly, estrous phase does not influence rats’ accuracy in a delayed response working memory task, performance on which is correlated with impulsive choice ( Shimp et al, 2015 ; Blaes et al, 2019 ).…”

“…Finally, it should be noted that previous studies have not evaluated sex differences in intertemporal choice in Fischer 344 × Brown Norway F1 hybrid rats, and thus it is possible that sex differences are particularly pronounced in this strain. Sex differences in many aspects of cognition (including other forms of cost-benefit decision making) have been observed in several rat strains ( van den Bos et al, 2012 ; Peak et al, 2015 ; Orsini et al, 2016 ; Blaes et al, 2019 ; Liley et al, 2019 ), and several studies have shown differences in impulsive choice between rat strains ( Huskinson et al, 2012 ; Garcia and Kirkpatrick, 2013 ). To our knowledge, however, no studies have directly compared sex differences in impulsive choice between strains, suggesting that this will be an important avenue of future research.…”

“…Rats were acclimated in this facility and handled for at least one week prior to initiation of any procedures. Group sizes were based on previous work from our labs that has assessed sex differences in decision making and PFC-dependent cognition ( Orsini et al, 2016 ; Blaes et al, 2019 ). In this work, n = 8 rats/sex was determined to be needed to detect sex differences.…”

Effects of repeated adolescent exposure to cannabis smoke on cognitive outcomes in adulthood

“…Despite the prevalence of cannabis smoking in humans, there have been relatively few assessments of the effects of cannabis smoke on behavior in preclinical models. Acute cannabis smoke exposure in rodents causes hypothermia, analgesia, and changes in locomotor activity, as well as alterations in cognitive performance (Blaes et al, 2019; Bruijnzeel et al, 2016; Niyuhire et al, 2007; Varvel et al, 2005). Similar results have been obtained with models of THC or cannabis extract vapor inhalation (Freels et al, 2020; Manwell et al, 2014; Nguyen et al, 2016; Taffe et al, 2020).…”

Eight-Section Brocade Exercises Improve the Sleep Quality and Memory Consolidation and Cardiopulmonary Function of Older Adults With Atrial Fibrillation-Associated Stroke

“…We chose the baseline characteristics [age (Hokett and Duarte, 2019; Scullin et al, 2019), gender (Spencer, 2008), high blood pressure (Borda et al, 2019; Kumar et al, 2019), high blood lipids (Reijmer et al, 2009; Kruisbrink et al, 2017), diabetes (Margolis et al, 2019; Zhu et al, 2019), being overweight (Mora-Gonzalez et al, 2019; Yeo et al, 2019), atrial fibrillation (Takii et al, 2016; Yeung et al, 2019), smoking (Blaes et al, 2019; Cohen et al, 2019), family history of stroke (Baumann et al, 2012; Reeves et al, 2014), and history of transient ischemic attack (Takahashi et al, 2009; Sico et al, 2017)] according to previous reports indicating that these parameters would affect sleep and memory. The statistical difference for baseline characteristics was insignificant between the two groups (Table 1, p > 0.05).…”